Differential microphone-transmitter.



J. J. 00mm. v DIFFERENTIAL MICROPHONE TRANSMITTER.

APPLIUATION FILED OUT. 24, 1910. 1,033,085, Patented July 23, 1912.

2 8KEETS-SHBET 1.

VV/TNES'EJ fw/zzvrofi:

I fiTTQR/VEYS,

J. J. OOMER.

DIFFERENTIAL MICROPHONE TRANSMITTER.

APPLICATION FILED 001224, 1910 Patented July 23, 1912,

: wywfii WITNESSES I ter has a perimeter or "edge '0 UNITED STATES PATENT OFFICE.

JOHN J. COMER, OF CHICAGO, ILLINOIS, ASSIGNOR T0 AUTOMATIC EN-UNCIATOR COMPANY, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

DIFFERENTIAL MICROPHONE-TRANSMITTER.

Losses;

Specification of Letters Patent.

Patented July 23, 1912.

Application filed October 24, 1910. .Serial 110.588,?87.

To all whom it may concern:

Be it known that I, JOHN J. Corina, a citizen of the United States of America, and resident of Chicago, Cook county, Illinois, have invented a certain new and useful Improvement in Differential Microplione lransmitters, of which the following is a specification.

My invention relates to telephone transmitters of the kind ordinarily known as differential transmitters.

Generally stated, the object of my invention is to provide an improved andhighly etlicient form' of differential transmitter adapted more particularly for use in loud speaking telephone systems, or in loud transmission systems for music, as insuch systems heavy currents are often necessary, and

purity of tone and clearness of enunciation are important and desirable.

It is also an object to provide a construction which will be simple and economical to manufacture, which will facilitate the assembling of the parts, and which will afford easy access thereto, for various purposes, as, for example, in filling the microphone box with granular carbon or similar material.

To these and otheruseful ends, my in vention consists in matters hereinafter set forth and claimed.

In the accompanying drawings Figure 1- is a longitudinal section of a difierential microphone transmitter embodying the principles of my. invention. Fig. 2 is a rear elevation of the said transmitter with the casing thereof'removed .to show the microphone. Fig. 3 is a perspective of the different parts of the microphone. Fig. 4 is a view similar to Fig. 1, showing another form of my invention. Fig. 5 is a rear View (similar to Fig. 2) of the transmitter shown in Fig. 4. Fig. 6 is a to Fig. 3) of the parts of the microphone shown in Figs. 2, 4 and 5.

As thus illustrated, and referring to Figs. 1 t0 3, inclusive, my invention comprises a front plate A having a central aperture (1 for the usual mouth piece a The metal diaphragm B is insulated from the plate A and held in place by a'disk O, which latthat bears against the diaphragm, to hold the same in place, and a central aperture 0. The insulationc is applied to the edge portion of lava ringc, and into the disk C hole 6 perspective (similar e and the third ,e", the circuits being of any suitable charrib (Z that bears against the insulation to firmly clamp the disk C anddiaphragm together and against the shoulder a? on the inside of the plate A, but with insulation a .separating the diaphragm from the plate The ring D has a screw threaded edge d that engages the threads (Z on the inside of the plate A.

The differential microphone E comprises a lava ring 0, a back carbon disk or electrode 6 closing, the rear end of said ring, a metal terminal disk or plate a separating said electrode from r and a back plate or metal clamping disk 6 bearing against said mica disk. The frontof the ring is closed by a disk of carbon 6 which serves as the front electrode, a metal terminal disk or plate 6 bearing against the said front electrode, and a mica disk 6 caring against and covering said metal disk. The clamping or binding screws 0 extend through all said electrodes and disks of the box thus formed, and through the at points around the openings 0 in the center thereof. The plunger 6 is of carbon, and is dis posed centrally of the interior of the box, and is connected by a stem 6 with the center of thediaphragm. This stem extendsthrough holes a in the front electrode e and the mica disk 6 which holes are closed around the stem with fiuffy asbestos or other suitable material. The ring c has a lateral for the introduction of the granular carbon c into the interior of the micro-' phone box after the same is fully assembled This is easily done as the said box is disposed on the back of the disk C and is easily assembled.

The back of the transmitter is closed by a cap or cover F in the usual manner.

the disk C, and a-clamping ring D has a the mica disk or plate ct,"

In use one terminal Wire goes to theplate or disk C, another goes to the terminal plate goes to the terminal plate acter.

The construction of the transmitter is si'rnple and strong and facilitates assembling of the different parts. Also, the construction of. the microphone box permits the use of heavy currents, and the raising, of the box' to ,a high temperature, without danger.- This is important, as in loud transmission such currents'are often necessary, and-in answer. descrlbed, is especially adapted for loudtransmissi'on, e ther for speaking or for such case the ordinary transmitter will not A differential transmitter, such as The construction in Figs. 4 to 6, inclusive, is practically the same as that previously described. In this case, however,the central or middle electrode G is not connected to the middle of the diaphragm II, but isconnected by four spider arms 9 with the said diaphragm at points on the latter equidiss tant from the center thereof. Also, in this case, vthe ring I is made in two parts, i and i, which leave openings 2' between them for the arms 9. These arms extend through openings 9 in the clamping plated, which latter corresponds to the clamping plate C of the previously described construction.

Thus the amplitude of vibration of the electrode G is not as great as that of 6- but the vibration is somewhat more powerful, and

the center of the'diaphragm is left free and clear to receive the vibrations. The vibra tion is a little more powerful this Way, be-

cause the diaphragm isv used as a lever, the.

connection to the electrode G being between the fulcrum and the power, the rim of the diaphragm being the fulcrum, and the power being applied at the center of the diaphragm where the vibrations impinge thereon,

Thus it will be seen that bymy invention I provide a differential microphone transmitter of high efiiciency and adapted for-use in loud transmission systems.

WhatI claim as my invention is:

1. In a transmitter, a diaphragm, a plate bearing against the margin of said diaphragm, to hold the latter inplace, a differential microphone on the back of said plate, and connections between said diaphragm and microphone, which connections are eccentric of the diaphragm. 2. In a transmitter, a tionary differential microphone, and a pludiaphragm, a Sta-- rality of connections from said microphone to said diaphragm,.said connections eccentrio of the diaphragm.

3. In a transmitter, a diaphragm, a clamping disk therefor, a pair of stationary electrodes, a ring for spacing said electrodes apart, a metal plate back of each. electrode, a mica plate outside of each metal plate, screws extending through said ring and electrodes and plates, and into said disk, to

clamp the same upon the said disk, a mov able electrode between said electrodes, granular carbon between all said electrodes, and

means connecting said movable electrode with said diaphragm.

4. In a transmitter, a diaphragm, differential microphone includinga pair of stationary electrodes and a movable electrode located between said stationary electrodes, and connections from said movable electrode to said diaplnragm at points eccentric of said diaphragm.

5. In a transmitter, a diaphragm, a cartrodes and a movable electrode located between said stationary electrodes, and connections from saidmovable electrode to said diaphragm at points eccentric of said diaphragm. I

Signed by me at Chicago, Illino s, this 12th day of October, 1910. I

JOHN J. OOMER. Witnesses:

WM. 13. DURNION, E. H. CLEGG.

(topics of this patent inay be obtained for five cents each, by addressing the Commissioner of Eatents, Washington, D. C. 

